Heat sink



FIG. 1 is a front side elevation view.

FIG. 2 is a right side elevation view.

FIG. 3 is a top plan view.

FIG. 4 is a bottom plan view; and,

FIG. 5 is a perspective view.

The rear side elevation view is omitted because it appears the same wayas the front side elevation view. Likewise, the left side elevation viewis omitted because it appears the same way as the right side elevationview.

The broken line showing of the environment is for illustrative purposeonly and forms no part of the claimed design.

The ornamental design for a heat sink, as shown and described.